SU298123A1 - METHOD OF OBTAINING POLYOLECHINES - Google Patents

Description

This invention relates to npdHSBOActey of high molecular weight solid polymers with beneficial mechanical properties | MI, by polymerizing ethylene or co-polymerizing ethylene with other alpha-olefins.

It is well known that ethylene can polymerize to form high molecular weight products. At low pressure in the presence of a mixed catalyst, alkyl aluminum dichloride and four titanium chloride or tetraalkoxy titanium are part of koToporo.

When obtaining higher ethylene polymers on a mixed catalyst consisting of alkylaluminum dichloride and trialkoxytitanium chloride, the yield of the measured product per weight unit of the catalyst used, as well as the density of the polymer product, increase.

However, the polymerisation activity of such a mixed catalyst is rather low, and the resulting polyethylene contains in the polymer chain branching and double bonds that violate its crystalline structure and reduce its density, which leads to a significant deterioration of the mechanical properties, which are characterized by resistance to deformation under the influence of mechanical

load, such as resistance to deformation under the influence of compression.

Therefore, the resulting polyethylene can not be applied in such cases when required

high mechanical properties, for example for manufacturing various types of containers. Such a limited applicability of the product causes great inconvenience in the case of the production of polyethylene on an industrial scale.

For the preparation of polyethylene, essentially free of branches and double bonds, the polymerization of ethylene is carried out in the presence of a mixed catalyst containing alkyl aluminum dichloride, alkyl alkoxy aluminum chloride and four titanium chloride.

compound of tetravalent titanium.

The molecular structure of the polyethylene obtained by the proposed method contains

undoubtedly a few branches and double bonds compared with the molecular structure of polyethylene obtained by a known tool characterized by the use of a mixed catalyst containing alkyl:

aluminum dichloride and four-trichloride. titanium or titanium compound. As shown in

tab. 1, such polyethylene contains, in essence, only methylene groups (-CH2 -), - located, in the form of linear

Table 1

Note. Presence of molecular

As can be seen from the table. 2, α-polyethylene, obtained by the proposed method, undoubtedly has a higher density and useful mechanical properties, such as improved

rigidity.

table 2

 Measured by the method of determining JIS K6760 with a sample of material having an intrinsic viscosity of 1.2.

 Measured by the ASTM D 747-63T method with a sample of material having an intrinsic viscosity t 1,2.

In addition, during the implementation of the proposed process, it becomes possible to control the molecular weight distribution of polyethylene, which determines to some extent the impact strength and formability of the polymer, for example, the resistance of molded products to preserve their original dimensions by adjusting the type of tetravalent titanium compound and adjusting the ratio components upon receipt of the mixed catalyst, as shown in the table. 3

Table 3

 Molar ratio

 , / Mn. Determination carried out on a gel chromatograph (Gel Permeation Chromatograph, Product of

The relationship between the average molecular weight and the factors characterizing the average molecular weight is noted.

Thus, a process for the preparation of solid high molecular polymer products with high density and excellent mechanical properties is envisaged, which consists in the fact that the polymerization of ethylene or its copolymerization with other alpha-olefins is carried out in the presence of a biased catalyst consisting of an alkyl chloride n dichloride formulas RAlCls, where R-Ci-Sv-alkyl; alcoholic alkylamine chloride of the General formula R (OR) A1C1, where R-Ci-Sv-alkyl; Cj-Syu-alkoxy group and tetravalent titanium compounds of the general formula TiCln (OR) 4-n, where OR-Ci-Syu-alkoxygroup JA is an integer from O to 4.

The alkyl aluminum dichloride, which is the first constituent of the mixed catalyst, is selected, for example, from methyl aluminum, ethyl alloys, and n or isopropyl aluminum, -, iso, secondary, or tertiary butyl aluminum, - hexyl aluminum and and m-octyl aluminum. It is well known that alkyl aluminum dichlorides usually have dimeric structures in hydrocarbon solvents and in the vapor phase,

In alkoxyalkyl aluminum chlorides, which are the second component of the mixed catalyst, the alkyl group can be methyl, ethyl, "- or isopropyl,

H-, iso-, secondary or tertiary butyl, n-hexyl or n-octyl; the alkoxy group can be methoxyl, ethoxy, n- or isopropoxy, "-," 30-, secondary or tertiary butoxy, pentoxy, octaxyl or decyloxy.

It is known that the above alkoxyalkyl aluminum chlorides usually exist as dimers or trimers in hydrocarbon solvents and can be synthesized

in various ways, for example, in the interaction of dialkyl aluminum chloride and alcohol, as a result of the reaction between aluminum trialkyl, aluminum trichloride and aluminum trialkoxyoxide, as well as

between alkylaluminiumsquichloride and trialkoxyaluminium.

Compounds of tetravalent titanium, which are the third component of the mixed structures, were determined according to the method that will be described below.

catalyst include compounds characterized by the presence of an alkoxy group, such as methoxy, ethoxy, n- or isopropoxy, "-, iso-, secondary or tertiary butoxy, pentoxy, octoxy or decyloxy, for example tetramethoxy, tetraethoxy, tetra- {n- or "zoo -) - propoxy-, tetra- (n-, iso-, secondary or tertiary) -butoxy-, tetra-" - octaoxytitanium, trimethoxy-, triethoxy-, tri- (("- or isopropoxy) -, tri- (n-, iso-, secondary or tertiary) -butoxy-, dimethoxytitanium chloride, diethoxy-, di- (n- or isopropoxy) -, di- ("-, iso-, secondary or tertiary butoxy) -titandi lorid, methoxy, ethoxy, n- or isopropoxy, n-, iso-, secondary or tertiary butoksititantrihlorid and titanium tetrachloride or a mixture thereof.

In the practical implementation of the process, conventional polymerization processes characterized by the use of catalysts such as Ziegler catalysts can be conveniently applied. This means that the polymerization reaction can be carried out by casting ethylene or a mixture of ethylene and other alpha-olefins. IB contact With a mixed catalyst obtained by mixing alkyl aluminum chloride, alkoxyalkyl aluminum chloride and titanium compound in an inert solvent free medium.

As for the proportions in which these components that make up the mixed catalyst are mixed together, the molar ratio when mixed between RAICU and R (OR) A1C1 is preferably in the range from 1: 10 to 10: 1 and most preferably in the range from 1: 3 to 5: 1. The molar ratio between the sum of the aluminum compounds and the titanium compound is preferably selected from 2: 1 to 20: 1.

It is desirable that the components are mixed at a temperature selected from -20 to 150 ° C. There are no particular limitations on the order of mixing these components.

Inert solvents that may be used in the process include zliphatic, alicyclic, aromatic, or chlorinated hydrocarbons that are substantially free of impurities and contaminants that poison this type of catalyst, such as water. Typical examples of such inert solvents are pentane, hexane, heptane, octane, cyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, dichloroethane and chlorobenzene.

Although there are no particular restrictions regarding the temperature and pressure at which the polymerization process is carried out, it is desirable to observe the temperature chosen in the range from 0 to 200 ° C and a pressure not exceeding 100 atm.

When using a catalyst manufactured by treating a precipitated catalyst in a ball mill or preferably by pre-precipitating it

catalyst on the carrier, which mainly used powdered polyethylene, etc., can be easily obtained polymers with a density of 0.35-0.45 g / cm. The catalyst can be used in the amount of I weight. hours 3-10 about. including the inert solvent used to make the mixed catalyst. The weight ratio between the carrier and

the mixed catalyst is preferably in the range from 1: 0.6 to 1: 5.

Although the regulation of the molecular weight of the polymer product B process can be carried out by selecting the ratios between

components included in the catalyst, the temperature at which the polymerization process is carried out, etc., it is recommended to carry out the polymerization reaction in the presence of hydrogen, preferably in an amount of 5-40 vol. %, calculated on the volume of ethylene in the gas phase.

The polymerization reaction can be carried out batchwise or continuously. The copolymerization of ethylene with other alpha-olefins, such as propylene or butene-1, is easily carried out with

no more than these components

The seamstress. %

The intrinsic viscosity of polymers was determined in a solution of tetralin at 130 ° С.

The number of branches and double bonds was determined by infrared spectroscopy by measuring the absorption in films

0.3 mm thick, obtained by pressing polymers under pressure at a temperature of 200 ° C. The degree of absorption was measured at the following wavelengths (in microns) characteristic of the respective branching and double bonds:

Methyl branch7.25

Ethyl Branch12,98

- CH CH10.37

-CH CH211.00

C CH211.27

. 12.00

The number of links formed by these branches and double bonds on the

1000 carbon atoms, calculated according to the methods described in the literature. Methyl Branch: Instrumental Analysis of High-Molecular Polymers Volume 1P, p. 100, (1965), Hirokawa.

Ethyl branch. J. Pol. Sci. 34, 569 (1959). Double bonds Anal. Chem., 26, 1887 (1954).

Example 1. To prepare a catalyst, 25 ml of m-heptane, 3.05 g (24 mmol) of ethyl aluminum dichloride and 1.36 g (4 mmol) of tetra-nbutoxytitanium at room temperature in a stream of argon, are successively placed in a 50 ml glass separatory funnel with a capacity of 50 ml. after which the resulting mixture

after mixing, no precipitate is formed, the mixture only turns a light yellow color, after 24 hours a large amount of dark brown fine-grained clear precipitate is released. 475 ml of n-heptane are placed in a 1 L glass flask equipped with a thermometer, a stirrer, feed and discharge tubes for gas, and the protonated mixed catalyst is heated to 60 ° C and ethylene gas is passed through. through columns filled with silica gel and molecular sieves. During the entire period of the polymerization reaction carried out with stirring, the temperature of the reaction mixture in the flask is maintained at 60 ° C, and the flask is cooled with water to remove the heat released during the polymerization.

After passing ethylene for 90 minutes, the catalyst is destroyed with 20 ml of butanol. To the resulting polyethylene was added 500 ml of 1 N hydrochloric acid solution. Example 4. As in Example 1, in a 50 ml glass separatory funnel from 25 ml of n-heptane, 1.53 g (12 mmol) of ethyl aluminum dichloride, 2.11 g (12 mmol of ethyl ethoxy aluminum chloride and 1.36 g (4 mmol) of tetra-c-butoxytitanium, after one hour of standing for 24 hours, a large amount of catalyst is obtained — dark brown fine-grained precipitate. Using the catalyst obtained and the wire, experience g white, oh. powder polyethylene with intrinsic viscosity rj 7,3. The content of branches and double bonds in it (in units / 1000С): The branches are less than 0.1 -CsHs "1.0 Double bonds" 0.01 -CH CH2 "0.01" 0.01 0.01 Examples 5-25. The polymerization of ethylene is repeated using the same equipment and the same technique as in example 1, but with different types of alkyl aluminum dichlorides and titanium compounds. The results are given in Table 5. ...

in butanol and heat the mixture for 4 hours under reflux. The polyethylene is filtered off and dried Hori 55 ° C in vacuum for 12 hours. 65 g of white powdered polyethylene are obtained, characteristic viscosity TI 7.3. The content of branches and double bonds in it (units / SOOO C): Branches

-Snz

2.0

C2H5 less than 1.0

wars

0.13

0.18

0.11-CH

less than 0.01

Examples 2, 3. Analogously to Example 1, but replacing tetra - "- butoxytitanium with 4 ml of trine-butoxytitanchloride or 4 ml of titanium tetrachloride, ethylene is polymerized. The results are shown in Table. four.

Table 4 Examples 26, 27. As in Example 1, but ethylene is polymerized at different temperatures (Table 6). Example 28. Copolymerization of ethylene with propylene. 475 ml of c-heptane and a mixed catalyst prepared as in Example 1 by passing a stream of gaseous nitrogen at 20 ° C, after which the contents of the flask are heated, are placed in a 1-liter glass flask equipped with a thermometer, a stirrer, and tubes for the supply and removal of gas. to 60 ° C and pass a gaseous mixture of ethylene with 2 mol. % propylene, pre-dried by passing through silica gel columns and molecular sieves. The polymerization reaction is carried out with stirring, while maintaining the temperature of the reaction mixture at a level of 60 ° C by cooling the flask with water to remove the heat released during polymerization. After passing the gaseous mixture for 90 minutes, the catalyst is decomposed by adding 20 ml of butanol. To the obtained polymer, 500 ml of a 1 N solution of hydrochloric acid in butanol are added and heated under reflux.

a s h o h

eleven

Then the polymer is filtered off, dried for 12 hours at 55 ° C under vacuum, and 33 g of a white powder with characteristic viscosity τ | 1.2. Contents of branches and double bonds in units / 1000С:

9.2

less than 1.0

„0.01

„0.01

„0.01

„0.01

As can be seen from the above data, the polymer obtained contains 9.2 units. methyl branches per 1000 C atoms, with 1.9 mol% being polymerized. % propylene. The density of the copolymer product is 0.95 g / cm.

Example 29. Reproduction of Example 28, following the procedure described therein, but in addition to ethylene, 2 mol. % n-butene-1 instead of propylene.

The result is 31 g of a white, powdered polymer, with an intrinsic viscosity of 1.1. Content of branches and double bonds: (units / KEP):

Branching

-СНз9.0

-CsHs8,2

Double bonds

- CH CH = less than 0.01

С СН2 „0.01

,, 0.01

С-СН- „0,01

According to the above data, it can be determined that the resulting polymer contains 8 units. ethyl branches per 1000 carbon atoms, moreover, олим6 mol. % and butene-1. The density of the copolymer product is 0.951 g / comp.

Example 30. In a 200 ml glass conical flask, 20 g of polyethylene with a particle diameter of 150 microns, 100 ml of commercially available heptane, 3.08 g (10 mmol) of three - "- butotitanium chloride, and 2.54 g (2. 20 mmol of ethyl aluminum dichloride in the indicated sequence at a temperature of 30 ° C and passing a stream of nitrogen gas. The mixture is stirred for 24 hours. A 5 l stainless steel autoclave is charged with 2.5 liters of heptane of a commercially available variety, 5.46 g (40 mmol)

12

Table 6

ethyl ethoxy aluminum chloride and prepared mixed catalyst in this sequence, after which the mixture is heated to 60 ° C. Then ethylene is passed into the autoclave at a rate of 200 g / h. The limerization reaction is carried out with stirring and simultaneously passing hydrogen gas in such an amount that its content in the ethylene gas phase is 30 vol. %

0 The temperature in the autoclave is maintained at 60 ° C during the entire course of the reaction, cooling the autoclave with water to remove the heat released during polymerization. After passing gaseous ethylene in

5 for 7 hours, the catalyst is decomposed with 100 ml of n-butol "ol. To the resulting polyethylene was added 2.5 liters of a 1 N solution of hydrochloric acid in butanol, and the resulting mixture was heated for 4 hours with a reverse cooling system. The resulting polyethylene is filtered off and the substance is kept for 12 hours at 55 ° C in vacuum, 1.45 kg of white powdered polyethylene are obtained, the density is 0.38 g / cm, the characteristic viscosity is 1.2. Polymer ash

150 ppm, the content of branching and double bonds was essentially the same, as described in Example 18. The average particle diameter of the polymer is 135 microns. Example 31. In a 4 L glass flask

0 put 400 g of powdered polyethylene with an average particle diameter of 90 microns, 2.0 l of heptane of commercially available varieties, 61 g (0.2 mol) of three-n-butoxytitanium chloride and 51 g (0.4 mol) of ethyl aluminum dichloride in the reduced sequence at a temperature of 60 ° C and passing a stream of gaseous nitrogen. The resulting mixture is stirred.

3 hours

A 100 liter stainless steel autoclave is charged with 50 l of heptane of a commercially available grade, 109 g (0.8 dgol) of ethyl aluminum chloride and the resulting catalyst in the sequence, then the mixture is heated to 60 ° C. Then ethylene is introduced into the autoclave at a rate of

4kg1h The polymerization reaction is carried out with stirring and simultaneously passing hydrogen gas in such an amount that its content in the ethylene gas phase is 15 vol. % The temperature in the autoclave is maintained at 60 ° C during the entire course of the reaction by cooling from the outside. After passing ethylene gas for 6 hours, its feed is stopped, the catalyst is decomposed in the usual way, and the ash is removed. The polyethylene is separated by centrifugation and dried. 22 kg of white powdered polyethylene with a density of 0.43 g / cm, a characteristic viscosity t of 2.3, an ash content of 100 ppm and an average particle diameter of 250 w / s are obtained. The content of the branches and double bonds was essentially the same as that of the polymer in Example 30. The invention method for producing polyolefins is by polymerizing ethylene or copolymerizing it with alpha-olefins in an inert hydrocarbon solvent in the presence of an organometallic complex catalyst, characterized in that In order to increase the density, linearity and yield of polymers, a catalyst consisting of dichlorine Ci-Cv-alkyl aluminum, Ci-Ciu-alkoxy-C-Cv-alkylaluminum and tetrachloride chloride is used. titanium and tetra- (C1-Syu-alkyl) titanates; mono-, di-, or trichloride tri-, di- or mono- (C) -Cyu-alkoxy) titanium.